How can I tell? I know the tread is getting kind of thin, but how thin is too thin? I don’t want to get a new set if these are going to last another 10,000 miles. Any rules of thumb for how to know when you need a new set of tires?
Well, one old rule of thumb used to be that the tread is gone if you can’t obscure a paper match head within. I’d bet there are more rigorous measures available, though.
The old rule of thumb was to put a penny in the grooves with Abe’s head pointing down. If you could see the top of his head, it’s time to get new tires.
More importantly is HOW the tires are wearing. The way they wear can tell you a lot about the state of the shocks/struts and other front end bits.
There are tread wear indicators built into the grooves of the tread. When the tread is worn down to the level of the indicator bars, the tire is officially worn out.
Most garages will have a guage that they can accurately measure the tread height and tell you, based on your tire type, how much longer you have. I assume this is more reliable than match and Abe’s heads, though I never thought about looking for indicators before! Just pull in and ask them to check - it shouldn’t take more than a couple of minutes.